Objective: To evaluate the clinical and prognostic role of homocysteine in pregnant women with prolonged pregnancy. To study the features of delayed delivery and perinatal outcomes in this case, we analysed 96 pregnant women with prolonged delivery during 2013-2015., who gave birth to children in the period of 41-42 weeks. As a control group we examined 41 pregnant women, who, for clinical and demographic characteristics, did not differ from the comparison group, but with delivery in time 37-40 weeks. Thus, depending on the patient's gestational age they were divided into 2 groups: group 1 included 41 patients, delivering with the term of gestation 37-40 weeks, group 2 – 96 patients, delivering after 41- 42 weeks of pregnancy. The level of homocysteine in the group with prolonged pregnancy (10,76 mmol/L) exceeded the figure in the control group significantly (7,72 mmol/L) (p<0.05). Risk assessment by ROC-analysis and logistic regression allows to calculate the critical value of homocysteine (9,5 mmol/L) which is associated with a high risk of complications (area under the ROCcurve is more than 90 %). The proposed method for predicting complications by using homocysteine serum level has a very high sensitivity (87,5 %), specificity (84,21 %), positive and negative predictive significance (85,37 % and 86,49 %, respectively) relative to the diagnosis of high risk complications of prolonged pregnancy. Women with high homocysteine reliably showed adverse changes in the functioning of the fetoplacental complex. According to the chi-squared, the homocysteine level over 9,5 mmol/L recorded statistically significantly fewer pregnant women with normal levels of progesterone (χ2=17,2 at p<0,01). According to the conducted regression analysis of the relationship between size of homocysteine and pulsation index (PI) cord statistically approximated logarithmic regression model (exponential) type pulsation index PI=-0,04+0,89*log10(homocysteine). Designed interdependence which is gradually growing exponentially, shows that more than half the dispersion characteristics pulsation index (PI) cord can be explained by the change in the concentration of homocysteine blood, and the greatest growth function was observed in the range of more than 14 mg/l of homocysteine, where in most cases there were a disorder in the uterine blood flow (PI over 1 IU).